Root colonization dynamics of two ectomycorrhizal fungi of contrasting life history strategies are mediated by addition of organic nutrient patches

Here we investigated whether root colonization dynamics of ectomycorrhizal fungi (EMF) of contrasting life history strategies (i.e. early vs late successional dominants) were affected by resource availability, as mediated either directly via the soil, or indirectly via host nutrition. In a two phase experiment, Pinus muricata seedlings were co-inoculated with spores of early (Rhizopogon occidentalis ) and late (Tomentella sublilacina ) successional dominant EMF, with or without squirrel faecal pellets added as a nutrient source, in single chambers (Phase A) subsequently converted to split-root chambers (Phase B). R. occidentalis colonized seedlings earlier than T. sublilacina . R. occidentalis root tip numbers peaked then declined in both treatments, but earlier in the minus pellet treatment than the plus. T. sublilacina increased steadily regardless of treatment. In the split-root treatment, we found no response by R. occidentalis , and a complex response by T. sublilacina , suggesting that plant nutrition may affect colonization dynamics. The strategy of R. occidentalis may be to colonize roots early in high resource environments; whereas that of T. sublilacina may be based upon slower colonization rates and greater competitive ability. The effect of nutrient additions on R. occidentalis may be highly dependent upon their timing.